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rescue brome, rescue grass, rescuegras

Arizona brome

Habit Plants annual, biennial, or perennial; loosely cespitose or tufted. Plants annual; tufted.
Culms

30-120 cm tall, 2-4 mm thick, erect or decumbent.

30-90 cm tall, to 3 mm thick, erect.

Sheaths

usually densely, often retrorsely, hairy, hairs sometimes confined to the throat;

auricles absent;

ligules 1-4 mm, glabrous or pilose, obtuse, lacerate to erose;

blades 4-30 cm long, 3-10 mm wide, flat, glabrous or hairy on both surfaces.

retrorsely pilose, sometimes mostly glabrous, throats sometimes with hairs;

auricles absent;

ligules 1-4 mm, usually glabrous, obtuse, erose;

blades 8-18 cm long, 3-9 mm wide, flat, sparsely pilose on both surfaces or the abaxial surfaces glabrous.

Panicles

9-28 cm, usually open, erect or nodding;

lower branches shorter than 10 cm, 1-4 per node, spreading or ascending, with up to 5 spikelets variously distributed.

12-25 cm, somewhat contracted or open;

lower branches shorter than 10 cm, 2-3(5) per node, initially erect to ascending, spreading at maturity, with 1-2 spikelets variously distributed.

Spikelets

(17)20-40 mm, shorter than at least some pedicels and branches, elliptic to lanceolate, strongly laterally compressed, not crowded or overlapping, with 4-12 florets.

18-25 mm, elliptic to lanceolate, strongly laterally compressed, with 4-8 florets.

Glumes

smooth or scabrous, glabrous or pubescent;

lower glumes 7-12 mm, 5-7(9)-veined;

upper glumes 9-17 mm, 7-9(11)-veined, shorter than the lowest lemma;

lemmas 11-20 mm, lanceolate, laterally compressed, strongly keeled, usually glabrous, sometimes pubescent distally, smooth or scabrous, 9-13-veined, veins often raised and riblike, margins sometimes conspicuous, hyaline, whitish or partly purplish, apices entire or toothed, teeth acute, shorter than 1 mm;

awns absent or to 10 mm;

anthers 0.5-1 mm in cleistogamous florets, 2-5 mm in chasmogamous florets.

subequal, smooth or scabrous;

lower glumes 8-12.5 mm, 3-veined;

upper glumes 9.5-14 mm, 7-veined, about as long as the lowest lemma;

lemmas 9.5-14 mm, lanceolate, laterally compressed, prominently 7-veined, strongly keeled at least distally, glabrous or pubescent distally or throughout, marginal hairs, if present, longer than those elsewhere, apices entire or with acute teeth shorter than 1 mm;

awns 6-13 mm, sometimes slightly geniculate;

anthers 0.4-0.5 mm.

2n

= 42.

= 84.

Bromus catharticus

Bromus arizonicus

Distribution
from FNA
AL; AR; AZ; CA; CO; DC; FL; GA; IA; IL; KS; KY; LA; MD; MO; MS; NC; ND; NE; NJ; NM; NV; NY; OH; OK; OR; PA; SC; SD; TN; TX; UT; VA; HI; AB; NF; ON
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; NV; TX
[WildflowerSearch map]
[BONAP county map]
Discussion

Bromus arizonicus grows in dry, open areas and disturbed ground of the southwest, usually below 2000 m. Its range extends from California and southern Nevada into Arizona, New Mexico, and northern Mexico.

Stebbins et al. (1944) demonstrated that, like Bromus carinatus var. carinatus, B. arizonicus obtained three of its genomes from B. catharticus or a close relative, but the remaining three genomes are not homologous with those in B. carinatus, probably being derived from a species in a section other than Ceratochloa. The small anthers of B. arizonicus strongly suggest that most seed is produced by selfing.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Awns absent or to 3.5 mm long
var. catharticus
1. Awns (5)6-10 mm long
var. elatus
Source FNA vol. 24, p. 199. FNA vol. 24, p. 201.
Parent taxa Poaceae > subfam. Pooideae > tribe Bromeae > Bromus > sect. Ceratochloa Poaceae > subfam. Pooideae > tribe Bromeae > Bromus > sect. Ceratochloa
Sibling taxa
B. aleutensis, B. anomalus, B. arenarius, B. arizonicus, B. arvensis, B. berteroanus, B. briziformis, B. carinatus, B. caroli-henrici, B. ciliatus, B. commutatus, B. danthoniae, B. diandrus, B. erectus, B. frondosus, B. grandis, B. hallii, B. hordeaceus, B. inermis, B. japonicus, B. kalmii, B. laevipes, B. lanatipes, B. lanceolatus, B. latiglumis, B. lepidus, B. madritensis, B. maritimus, B. mucroglumis, B. nottowayanus, B. orcuttianus, B. pacificus, B. polyanthus, B. porteri, B. pseudolaevipes, B. pubescens, B. pumpellianus, B. racemosus, B. ramosus, B. richardsonii, B. riparius, B. rubens, B. scoparius, B. secalinus, B. sitchensis, B. squarrosus, B. sterilis, B. suksdorfii, B. tectorum, B. texensis, B. vulgaris
B. aleutensis, B. anomalus, B. arenarius, B. arvensis, B. berteroanus, B. briziformis, B. carinatus, B. caroli-henrici, B. catharticus, B. ciliatus, B. commutatus, B. danthoniae, B. diandrus, B. erectus, B. frondosus, B. grandis, B. hallii, B. hordeaceus, B. inermis, B. japonicus, B. kalmii, B. laevipes, B. lanatipes, B. lanceolatus, B. latiglumis, B. lepidus, B. madritensis, B. maritimus, B. mucroglumis, B. nottowayanus, B. orcuttianus, B. pacificus, B. polyanthus, B. porteri, B. pseudolaevipes, B. pubescens, B. pumpellianus, B. racemosus, B. ramosus, B. richardsonii, B. riparius, B. rubens, B. scoparius, B. secalinus, B. sitchensis, B. squarrosus, B. sterilis, B. suksdorfii, B. tectorum, B. texensis, B. vulgaris
Subordinate taxa
B. catharticus var. catharticus, B. catharticus var. elatus
Synonyms Ceratochloa unioloides, B. willdenowii, B. unioloides B. berteroanus var. excelsus
Name authority Vahl (Shear) Stebbins
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